1. Field
The present disclosure relates to novel data acquisition and image processing.
2. Description of Related Prior Art
The problem of ground-based fine-resolution imaging of geosynchronous satellites continues to be an important unsolved space-surveillance problem. If one wants to achieve 10 cm resolution at a range of 36,000 km at λ=0.5 μm via conventional means, then a 180 m diameter telescope with adaptive optics is needed (obviously prohibitively expensive). Disclosed is a passive-illumination approach that is radically different from amplitude, intensity, or heterodyne interferometry approaches. The approach, called Synthetic-Aperture Silhouette Imaging (SASI), produces a fine-resolution silhouette image of the satellite.
A silhouette is the image of an object represented as a solid shape of a single color (typically black) so that its edges match the object's outline. Silhouettes arise in a variety of imaging scenarios. These include images of shadows that are cast either on a uniform or a non-uniform but known background. Silhouettes also occur when an opaque object occludes a known background. This case is particularly evident when a bright background, such as the sun or the moon, is occluded by a relatively dark object, such as a satellite or an aircraft.
Various references reflect the state of the art in determining the silhouette of an object including (1) R. G. Paxman, D. A. Carrara, P. D. Walker, and N. Davidenko, “Silhouette estimation,” JOSA A 31, 1636-1644 (2014); (2) J. R. Fienup, R. G. Paxman, M. F. Reiley, and B. J. Thelen, “3-D imaging correlography and coherent image reconstruction,” in Digital Image Recovery and Synthesis IV, T. J. Schulz and P. S. Idell, eds., Proc. SPIE 3815-07 (1999); (3) R. G. Paxman, J. R. Fienup, M. J. Reiley, and B. J. Thelen, “Phase Retrieval with an Opacity Constraint in LAser IMaging (PROCLAIM),” in Signal Recovery and Synthesis, 1998 Technical Digest Series 11, 34-36 (Optical Society of America, Washington D.C., 1998); and (4) R. G. Paxman, “Superresolution with an opacity constraint,” in Signal Recovery and Synthesis III, Technical Digest Series 15, (Optical Society of America, Washington D.C., 1989);
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.